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45MBCAQ: Installation Instructions
6. Detection of flammable refrigerants
Under no circumstances shall potential sources of ignition be used in
the searching for or detection of refrigerant leaks. A halide torch (or
any other detector using a naked flame) shall not be used.
The following leak detection methods are deemed acceptable for
refrigerant systems. Electronic leak detectors that have a sensitivity
of 1/8 oz (5g)/year may be used to detect leaks of flammable
refrigerants. (Detection equipment shall be calibrated in a
refrigerant-free area.) Ensure that the detector is not a potential
source of ignition and is suitable for the refrigerant used. Leak
detection equipment shall be set at a percentage of the LFL of the
refrigerant and shall be calibrated to the refrigerant employed, and
the appropriate percentage of gas (25% maximum) is confirmed.
Leak detection fluids are also suitable for use in external leak
detection.
NOTE Examples of leak detection fluids are:
–- bubble method,
–- fluorescent method agents.
If a leak is suspected, all open flames shall be removed/extinguished.
If a leakage of refrigerant is found which requires brazing, all of the
refrigerant shall be recovered from the system, or isolated (by means
of shut off valves) in a part of the system remote from the leak. See the
following instructions of removal of refrigerant.
7. Evacuation
When breaking into the refrigerant circuit to make repairs or for any
other purpose, conventional procedures shall be used. However, for
flammable refrigerants it is important that best practice be followed,
since flammability is a consideration. The following procedure shall
be adhered to:
• safely remove refrigerant following local and national regulations;
evacuate
• purge the circuit with nitrogen
• evacuate (requirement)
• continuously flush or purge with nitrogen when using flame to
open circuit
• open the circuit
The refrigerant charge shall be recovered into the correct recovery
cylinders. Charging must be performed by liquid charging method.
For appliances containing flammable refrigerants, the system shall
be purged with oxygen-free nitrogen to render the appliance safe for
flammable refrigerants. This process might need to be repeated
several times. Compressed air or oxygen shall not be used for
purging refrigerant systems.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
For appliances containing flammable refrigerants, refrigerants
purging shall be achieved by breaking the vacuum in the system
with oxygen-free nitrogen and continuing to fill until the working
pressure is achieved, then venting to atmosphere, and finally pulling
down to a vacuum (requirement). This process shall be repeated
until no refrigerant is within the system (requirement). When the
final oxygen-free nitrogen charge is used, the system shall be vented
down to atmospheric pressure to enable work to take place. The
outlet for the vacuum pump shall not be close to any potential
ignition sources, and ventilation shall be available.
Recovery: When removing refrigerant from a system, either for
servicing or decommissioning, it is recommended good practice that
all refrigerants are removed safely.
When transferring refrigerant into cylinders, ensure that only
appropriate refrigerant recovery cylinders are employed. Ensure that
the correct number of cylinders for holding the total system charge
is available. All cylinders to be used are designated.
8. Charging procedures
In addition to conventional charging procedures, the following
requirements shall be followed:
• Work shall be undertaken with appropriate tools only (In case of
uncertainty, please consult the manufacturer of the tools for use
with flammable refrigerants).
• Ensure that contamination of different refrigerants does not occur
when using charging equipment. Hoses or lines shall be as short
as possible to minimize the amount of refrigerant contained in
them.
• Charging must be performed by liquid charging method.
• Ensure that the refrigeration system is grounded prior to charging
the system with refrigerant.
• Label the system when charging is complete (if not already).
• Extreme care shall be taken not to overfill the refrigeration
system.
• Prior to recharging the system it shall be pressure tested with
oxygen free nitrogen (OFN). The system shall be leak tested on
completion of charging but prior to commissioning. A follow up
leak test shall be carried out prior to leaving the site.
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